This invention is generally directed to the field of capacitors for integrated circuits and semiconductors, and is more particularly directed to the field of vertically integrated capacitors in such circuits and semiconductors.
It is a well known in the filed of implantable medical devices that device volume and electrical energy consumption must be minimized if the implantable device is to prove efficacious and beneficial. Moreover, implantable medical device reliability must be high, as patient""s lives often literally depend on the continuing operation of the device. Additionally, manufacturing and material costs in such devices must be held to a minimum if they are to be affordable and therefore available to a wide range of patients having different demographic characteristics.
Semiconductors are employed extensively in many implantable medical devices. Because most implantable medical devices either sense or deliver electrical charges or electromagnetic fields to various types of human tissue, capacitors find widespread application in these devices. Owing to total charge capacity and other requirements, however, such capacitors are often difficult or impossible to physically integrate on a cost-effective basis into the semiconductor materials employed to form the integrated circuits or chips widely employed in implantable medical devices. Instead, off-chip capacitors are typically employed that are wire-bonded to integrated circuits. Among other things, such off-chip capacitor configurations result in increased parasitic capacitances, high switching losses, and significant increases in the volumes and areas of integrated circuits owing to the presence of wire bond pads and physically large capacitors. What is needed is a means of eliminating off-chip capacitors in implantable medical and other devices, thereby reducing the cost, physical size and volume of such devices.
Patents and printed publications describing various aspects of the foregoing problems and the state of the art are listed below.
1. High-Value MOS Capacitor in Ultra-Deep Trenches in Silicon to Rosseboom et al., Philips Research.
2. U.S. Pat. No. 5,394,000 entitled xe2x80x9cTrench Capacitor Structurexe2x80x9d to Ellul et al.
3. U.S. Pat. No. 6,121,106 entitled xe2x80x9cMethod for Forming an Integrated Trench Capacitorxe2x80x9d to Ellis.
4. U.S. Pat. No. 5,964,787 entitled xe2x80x9cStimulus with Controllable Switched Capacitor Output Stagexe2x80x9d to Kerver et al.
5. U.S. Pat. No. 5,948,004 entitled xe2x80x9cImplantable Stimulator Having an Efficient Output Generatorxe2x80x9d to Weijand et al.
6. U.S. Pat. No. 5,941,906 entitled xe2x80x9cImplantable Modular Tissue Stimulatorxe2x80x9d to Barreras et al.
Broadly, it is the object of the present invention to provide an improved integrated circuit for implantable medical and other devices which eliminates or substantially reduces the number of off-chip capacitors. It is a yet further object of the present invention to provide an integrated circuit for an implantable medical or other device, which is smaller and less expensive than prior art integrated circuits.
All patents and printed publications listed hereinabove are hereby incorporated by reference herein, each in its respective entirety. As those of ordinary skill in the art will appreciate readily upon reviewing the drawings set forth herein and upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, at least some of the devices and methods disclosed in the patents and publications listed hereinabove may be modified advantageously in accordance with the teachings of the present invention.
Various embodiments of the present invention have certain objects. That is, various embodiments of the present invention provide solutions to problems existing in the prior art, including, but not limited to, the problems listed above.
Various embodiments of the present invention have certain advantages, including, without limitation, one or more of: (a) reducing the size of devices which include integrated circuits; (b) reducing the number of wire bond pads; (c) increasing the manufacturing yield of devices which include integrated circuits as a result of reducing the number of wire bond pad connections that must be made; (d) increasing the density of integrated circuits; (e) reducing the cost of integrated circuits; (f) reducing the size of implantable medical devices; and (f) increasing the reliability of implantable medical devices.
Various embodiments of the present invention have certain features, including one or more of the following: (a) deep trench floating capacitors formed in semiconductor materials; (b) high aspect ratio deep trench floating capacitors formed in semiconductor materials; (c) deep trench non-floating capacitors formed in semiconductor materials; (b) high aspect ratio deep trench non-floating capacitors formed in semiconductor materials; (c) integrated circuits connected to a minimum number of off-chip capacitors via wire bond or other means; (d) on-chip input capacitors for implantable medical stimulators and defibrillators; (e) on-chip output capacitors for implantable medical stimulators and defibrillators; (f) on-chip power supply bypassing and decoupling capacitors; (g) on-chip charge transfer capacitors; (h) on-chip charge storage capacitors; and (i) on-chip DC blocking output capacitors.
Floating and non-floating on-chip capacitors are formed by vertical walls and/or large aspect ratio trenches disposed in semiconductor material. By optimizing the through spacing and substrate voltage, a very small parasitic to intended capacitance ratio may be obtained. Capacitors so formed may be used as on-chip charge storage and other types of on-chip capacitors, and eliminate or reduce the number of off-chip capacitors that would otherwise be required. The capacitors find particularly efficacious application in implantable medical devices where volume, cost and electrical energy consumption must be minimized.